


the science says no (my heart says yes)

by Anonymous



Category: Johnny Test (Cartoon)
Genre: F/F, Incest, Sibling Incest, johnny test more like johnny incest hahaha, why the fuck am i writing johnny test incest fanfiction
Language: English
Status: Completed
Published: 2018-01-12
Updated: 2018-01-12
Packaged: 2019-03-03 20:30:06
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 2,744
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/13348950
Author URL: https://archiveofourown.org/
Summary: The truth is, her pretended interest in Gil aside, Mary Test has only ever had eyes for one person.She's perfect. So smart, the smartest person Mary knows. And so beautiful, in that adorably oblivious, geeky kind of way.Mary just wishes they didn't share 100% of their DNA.





	the science says no (my heart says yes)

**Author's Note:**

> why did i write this

“With _this_ neural manipulator, we can quite literally rewire Gil’s brain so that the sight of _any_ other person but us won’t have even the slightest arousing effect on him. He won’t be able to fall in love with anyone _but_ us!” Susan squealed.

Mary smiled at her twin sister.

“You’re so smart.” She said.

Susan cocked her head.

“Sure. It’s not like I built it all by myself, though. It was a team effort. Like…everything we do.”

“Right, right. I know.”

“You don’t sound particularly excited, Mary.” Susan said, a little concerned.

“I’m just a little tired. You know, barely got any sleep last night.”

In truth, Mary _was_ tired. She was long since tired of pretending she _wanted_ their blond neighborhood airhead in the first place. Gil Nexdor was a perfectly nice, if dumb, kid, and a _very_ nice- _looking_ one, but he’d just never gotten Mary’s heart going the way he did Susan’s.

But she’d dutifully played along, expertly mimicking Susan’s youthful infatuations. It was almost fun sometimes, seeing how convincingly she could act out lust for Gil. But it was getting tiresome. Yet she would live the lie until her dying day if she had to, because Gil was all Susan ever thought of. And Mary would do anything to keep Susan by her side.

After all, it wasn’t like she could just come out with the truth. What kind of psycho falls in love with her own twin sister?

* * *

The neural manipulator, like every other one of the countless inventions the twins had whipped up in their fruitless quest to win Gil’s affections, failed miserably.

They lured Gil into Porkbelly Park with the help of a few fake flyers advertising a non-existent skating competition. Once the simple-minded heartthrob put in his appearance, the two redheads fixed the sights of their new machine and fired a beam of concentrated energy through the golden-haired Adonis’ vacuous skull.

As it turned out, Johnny had wandered into the lab a few hours later and, mistaking the contraption for a soft-serve dispenser, fiddled with a few of the knobs and buttons. The new settings, instead of narrowing Gil’s sexual orientation to exclude everyone but them, caused him to be struck with serious illness at the sight of everyone but them.

A few hours, a time machine, a visit from Mr. White and Mr. Black, and a serving of their father’s awful meat loaf later, everything was back to normal. Including Gil’s complete lack of interest.

The girls stepped back into their lab, the door hissing shut behind them.

Susan sniffled. She buried her face in her hands.

It took Mary a second to realize her sister was crying. She reached out and gently pulled Susan’s thick glasses from her fine nose, so she wouldn’t fog them up. Mary gently folded them up and placed them into her lab coat’s pocket. She reached out and pulled her twin into a hug.

“Hey…Susan, what’s wrong?”

“I don’t _understand_!” Susan sobbed. “Why doesn’t it _ever_ work? Why does he _always_ ignore us? Is it our personality? Are…are we ugly?”

Mary sighed. She put an arm around Susan’s shoulder and led her, still crying, out of the lab.

Stepping into their bedroom, she sat on the edge of her bed and motioned for her sister to sit down next to her. She reached out and wiped a few stray tears from Susan’s face, hoping she wasn’t overstepping.

“Please stop crying, Suzie.” Mary said. She sighed. “Can I tell you a secret?”

“Wh-what?” Susan asked through her tears.

Mary’s heart beat faster.

“I…I’ve never…never really liked Gil. Not really.”

The tears seem to freeze halfway down Susan’s face.

“What?”

Her mouth pops open into a little ‘o’ of surprise.

 _She’s so cute,_ Mary thinks, before shoving the thought deep, deep down.

“It’s true.”

“But…but…all these years! All those experiments! I don’t understand! Why pretend? What was the point?”

“Well, you liked him so much. You were always coming up with these ways to make him fall in love with us. And…well, I just wanted to spend time with you, so…”

Susan cocked her head. A little smile came over her lips. Her blue eyes sparkled.

“ _That_ much?”

“What?”

“You wanted to spend time with me _that_ much? To pretend for years?” Susan giggled.

“Well…yeah.” Mary replied, her heart drumming in her chest. “You’re my sister. And you’re the only person I know who’s as smart as me. Smarter, really. I could never have gotten _any_ of our inventions done without you.”

“Wow. That’s really sweet, Mary.” Susan said, her tears drying. She reached over and pulled her sister into a hug. Mary’s entire body electrified in her sister’s embrace. “And that’s not true, you know. That I’m smarter than you.”

“Well, what _is_ true is that I love you. And you don’t need to cry over Gil Nexdor.”

“So…you really never liked him? _Ever_?”

“Not like that. He’s a nice enough kid, but I never _liked_ him _liked_ him.” The next words spilled from her mouth before she could stop them. “The truth is–I’ve always kind of been head over heels for someone else.” As soon as she said it she mentally kicked herself. _Stupid_. _What are you going to say when she asks who it is_?

Sure enough, Susan’s eyes lit up. She brushed a few strands of bright red hair out of her eyes, perfectly framing those fine, lovely features that always put butterflies into Mary’s stomach.

“Really? Who is it?” Susan asked, elbowing her sister gently.

“It–it’s no one.” Mary stammered.

“Come on! I’m your sister! You know I won’t say anything! You can tell me.” She urged.

 _Right_. _You’re my sister. That’s the problem._

“I–it really doesn’t matter. What matters is that however blonde Gil’s hair is or however hot he is without a shirt, I can’t stand to see you torture yourself over him anymore. Suzie, you’re the smartest, most clever person I’ve ever met. And you are most definitely _not_ ugly. I could dig up that stupid facial measurement software we built two years ago and it would tell us that you’re the prettiest girl in this whole dumb town. But I don’t need to, because I already know it. If Gil doesn’t see it, that’s his problem. There are a hundred other boys who would kill to get a date with you, I promise. Er…not counting Eugene.”

Susan’s smile grew a little wider. It may have been Mary’s imagination, but she could swear she saw a little blush coloring her sister’s fair cheeks.

“You really mean all that?”

“Of course I do, dork.” Mary said.

“It really means a lot, Mary.”

“Do me a favor.” Mary said, putting a hand on her sister’s arm. “Forget about Gil. Just for a little bit. Try to think about other things. No inventions, no crazy schemes. Just try it for a week. Then we’ll see how you feel.”

“Okay.” Susan said. “I’ll think about it. But…I really have to know about this boy you like!”

Mary felt her cheeks burning.

“Come on, Susan, it really doesn’t matter. Does it?”

“It doesn’t _matter_ , but the curiosity is going to _kill_ me.”

“I _knew_ I shouldn’t have said anything.” Mary moaned.

“Okay, fine, don’t tell me his name. Just tell me a little about him.” Susan prodded.

Mary sighed.

“Well…fine.” She conceded. “They’re intelligent.”

“Intelligent as us?” Susan asked.

“Almost.” Mary said, wistfully.

“They’re really, really cute. Especially when they get excited about something, like a new project, they have these big, gorgeous eyes that just light up. It’s adorable. They can be a little bull-headed, sometimes, but I like that about them, in a way. It’s amazing how creative they are when they put their mind to something. They’re just…so wonderful. It’s amazing they’ve never had a boyfriend, really.”

“Wait…” Susan raised an eyebrow. “Did you say boyfriend?”

“Uh…” Mary stammered. Her cheeks burned bright red. Her mind reeled.

“This…person. Is it a girl?”

“I–well…I–uh.”

“Mary, are you uh…you know. Are you into girls?” Mary didn’t say anything. She just fixed her sister with her bright turquoise eyes, shining through the angular frames of her glasses. “Oh, Mary why didn’t you ever tell me!” Susan said. “You didn’t think I’d be upset or mad or anything, did you?” She asked, concerned. Susan reached out and squeezed her sister’s hand.

“No, that isn’t it. It’s just that I suppose I wasn’t ready yet. That’s all.”

Susan rubbed Mary’s hand; completely oblivious to the effect she was having on her.

“Well, come on! Tell me her name!”

“I can’t.” Mary sighed. “I just can’t.”

“Okay. I won’t push you anymore. Whoever it is, know that I support you. And whoever it is, they’d have to have an IQ of negative 150 to ignore you. Cause the only reason you think _I’m_ the prettiest girl in Porkbelly is because, smart as you are, you clearly don't know how to use a mirror.” Susan leaned in and kissed her sister on the forehead.

Mary felt her entire body stiffen. She almost swooned. Her stomach curled up into knots.

“I–I have to go.” Mary stammered.

“Why?”

“I just–I remembered something in the lab. You don’t have to come. Just get some rest. Feel better!”

Then Mary rushed out of the room.

Susan watched her go, confused.

“…Mary?”

* * *

The next morning, Mary, having spent all night in the lab tinkering with a dozen dead-end projects to take her mind off of Susan, stumbled out into the yard. She’d gotten no more than an hour or two of sleep. The sunlight burned itself into her eyes.

“Alright, Dukey! Come on! Throw it!” Johnny cried. The hyper-intelligent dog pulled his arm back and hurled the ball. Johnny’s arm extended like elastic, shot forty feet into the air and snatched the baseball down to earth. It was an impressive demonstration of the sisters’ new ‘stretch tech’ genetic modification procedure, which they’d, as usual, tested out on their brother.

“Oh, hey Mary.” Johnny said when he noticed his sister’s presence.

“Hey Johnny.” She groaned, her head throbbing. “Can I ask you something?”

Johnny shook his arm, restoring it to normal length.

“Sure. I guess. It’s not like you guys ask me stuff a whole lot.”

“It’s a question about…well…ugh…romance, I guess.”

“Oooh, Mary’s in _looooove_!” Johnny teased.

“Shut up, Johnny!” Mary barked, face red. “Ugh, this was a mistake.”

“No, wait, wait. I’m sorry. Go ahead. Ask me.”

“Mary asking Johnny for love advice? _Now_ I’ve seen everything.” Dukey quipped.

“Quiet, or I’ll take away your ability to talk again.” Mary threatened.

The dog quickly shut his mouth.

“So what’s up?” Johnny asked, sitting down on the grass.

“What if you really liked someone that you weren’t supposed to like?” Mary asked.

“Weren’t supposed to like? What do you mean, like Eugene or something?”

“Ew! No! Gosh! Just someone that it wasn’t considered _okay_ for you to like?”

“Well, I don’t consider it okay for you to like Gil.”

“Very funny. Anyway, it’s _not_ Gil. It’s someone else.”

“Well, what’s wrong with you liking them? Are they way older than you or something?”

"No! They're...just my age, actually."

“Well, what then? Look, Mary. I don’t know why you’re asking _me_. It’s not like I have any experience with romance.”

“I didn’t know who else to ask, okay?” She snapped.

“Well…even if you can’t be with them for whatever reason, you might as well tell them, right? I guess it can’t hurt. And it might help to get it off of your chest, at least. You know, clear the air.”

Mary blinked through her massive glasses.

“Wow. That’s…surprisingly insightful advice from you, Johnny.” She said, in awe.

“Well, you did ask.” He said.

“Thanks.” Mary replied. She stood, patted her brother on the shoulder, and reentered the house.

“Alright, Dukey!” Johnny exclaimed. “Let’s see how far these arms can _really_ reach! 

* * *

 

Mary waited until that night when her parents, brother, and talking dog were all asleep.

Susan was in the lab, working on a project completely unrelated to Gil, as per Mary’s suggestion.

“What’s that, there?” Mary asked as she stepped through the automatic door.

“Oh, just a little something that came to mind this morning. It’s a sort of…nutrition amplifier, if you will. It can amplify by ten times the amount of nutrients that would usually exist in most staple plants across the world. If my calculations are correct, this could be key in the reduction of malnutrition and starvation across the developing world.”

"You see?” Mary exclaimed. “This is what I’m talking about! You’re brilliant! If you put your mind to stuff like this rather than getting the poor ditz next door to like you, you could singlehandedly solve half the world’s problems! _We_ could!”

“You know…this whole ‘try to think less about Gil’ think you’ve prescribed is working. It’s like a positive feedback loop. The more time I spent obsessing over him, the more time I spent trying to figure out ways to woo him, and the more time I spent doing that, the more time I spent obsessing over him! It’s only been a day, but I already feel a little less stressed over the whole thing.”

"See?” Mary beamed. “You don’t need Gil or any other guy on earth to give you self-worth.” She squeezed Susan’s shoulder. “It’s about time you realized it, too.”

Susan turned away from her project and stared into her sister’s eyes. Mary’s heart began its furious beating again.

“Are you alright, Mary?”

“Huh? Why?” Mary asked, flustered.

“It’s just…the machine we installed. After we almost sent Johnny into cardiac arrest with those stamina pills a year ago. You know, that one that warns us if anyone’s heart rate is above normal?” Susan gestured to the ticker on the wall, displaying Mary’s rather erratic heartbeat.

“Nothing’s wrong, I’m just–“ Mary’s words failed her.

Susan elbowed her teasingly.

“You’re not thinking about your special someone, are you?”

“Um– “

“Come on. Won’t you tell me who it is?”

“I _can’t_ , Mary.” She said, though she wanted to more than anything.

“Is it because you think I won’t like her? Gosh, it’s not Sissy or something, is it?”

“Ew! No! She's like 12! It’s not that I think you won’t like _them_ , it’s that I don’t know if you’ll like _me_ liking them.”

“It’s not like I’ll be _jealous_ or anything! We’ve liked–well, pretended to like, apparently–the same guy for years without any issue.”

“It’s not jealousy either.” Mary said. Susan looked at her, blue eyes full of love and compassion.

 “What, then?”

“I’m not _supposed_ to like them. It’s…it’s genetically unadvisable, as a matter of fact.”

“Genetically…Mary, do I know her?”

“Yes.” Mary squeaked.

“Do I know them _well_?”

“Yes.” She admitted. “ _Really_ well.”

“Have I seen them lately?”

“I’d say so.”

Susan placed her hands on her sister’s shoulders.

“Mary, you know that no matter _who_ it is, I wouldn’t be angry or upset at you for liking them. You know that, right? And who knows? They might even feel the same way.”

“You think so?”

“Sure. So…tell me who it is?”

Mary sighed. She sucked in a deep breath. Then she leaned in and placed a light, chaste kiss on her sister’s lips.

“Oh!” Susan gasped. Then blood poured into her cheeks.

“I–I’m sorry.” Mary stammered. “I’m so sorry. I’ll go, now. I’m so sorry. I–“

“Wait.” Susan placed a gentle hand on Mary’s hip. “You don’t need to go anywhere.” She wrapped her arms around Mary’s waist and pulled her in, and then placed a kiss of her own, deeper and longer, on Mary’s lips. When the kiss ended, Mary stumbled back, mouth wide open, speechless. She fought for words. Susan smiled and kissed her again, this one shorter and gentler.

“Suzie, I–“

“Thanks for helping me get over Gil. In more ways than one. Now, just let me put the finishing touches on this project, and then I’ll make us some snacks, and we can watch a movie or something together. Just the two of us. Sound good?”

Mary smiled, slipping her glasses from her eyes so she wouldn’t fog them up with joyous tears.

“Sounds good.”


End file.
